FIGS. 1 to 3 show a so-called trunnion suspension dedicated to tandem axles and having a structure with a trunnion shaft 3 secured to frames 5 through trunnion brackets 4 between a pair of axles 1 and 2 arranged in a tandem along a front-rear direction, leaf springs 6 each being rotatably mounted at its central portion via a rotation base 7 over the trunnion shaft 3 to support the front- and rear-side axles 1 and 2 with opposite ends of the leaf spring 6, upper and lower rods 8 and 9 being arranged for retaining positions of the axles 1 and 2 in the front-rear direction.
A cross member 10 bridges the left and right frames 5 for reinforcement of the frames 5 at positions where the trunnion brackets 4 are secured. Upper rods 8 couple front and rear faces on a central portion of the cross member 10 to upper sides of central portions of the axles 1 and 2, respectively; lower rods 9 couple front and rear faces on lower ends of the trunnion brackets 4 to lower sides of opposite ends of the axles 1 and 2, respectively.
As a result, in such trunnion suspension, up-and-down movements of the front- and rear-side axles 1 and 2 are absorbed by the leaf springs 6; and forces in the front-rear direction are transmitted through the upper and lower rods 8 and 9 to the frames 5 with the leaf springs 6 rotating around the trunnion shaft 3. Thus, favorable driving over a bump is realized.
In the figures, reference numeral 11 denotes U-bolts for mounting the central portion of the leaf spring 6 on the rotation base 7; 12, mounts on the front and rear faces of the central portion of the cross member 10 for the upper rods 8; 13, mounts on the upper sides of the central portions of the axles 1 and 2 for the upper rods 8; 14, mounts on the front and rear faces at the lower ends of the trunnion brackets 4 for the lower rods 9; and 15, mounts on the lower sides at the opposite ends of the axles 1 and 2 for the lower rods 9.
Prior art documents related to this type of trunnion suspension are, for example, Patent Literatures 1 and 2.
Citation List
Patent Literature
[Patent Literature 1] Japanese Patent Publication7-266818A
[Patent Literature 2] Japanese Utility Model Publication 5-037511A